Jim,
        It sounds as if you're separating the pad from the substrate during the
component removal operation, correct?  What you did not mention was where
there was presence of the dye.
        Was there dye observed on the underside of the pads?  If so, check your
copper adhesion strength, pad size, etc.
        If you peel the pad off the solderballs, do you observe die across the
fractured solder interface?
        Keep in mind that your fracture mode from your sample preparation
(typically a fairly crude method of prying the component from the card) is
not necessarily the same as your component failure mode.  Look for the
presence of dye to find your component failure mode.
        Couple more thoughts
        ....do you use a vacuum chamber to aid dye penetration?
        ....make sure that the dye is fully cured prior to component removal.

Jeff Perkins




-----Original Message-----
From:   Maguire, James F [SMTP:[log in to unmask]]
Sent:   Wednesday, January 13, 1999 7:22 PM
To:     [log in to unmask]
Subject:        [TN] Dye Penetration Testing of BGA solder joints

As part of our BGA reliability testing we would like to perform dye
penetration testing of some of our BGA solder joints (typically after
they've seen vibration and/or thermal stress tests.)

I've seen references to dye penetration tests being done (and even photo's
of joints); what I am looking for is a reference to a person that actually
has done this.  We've tried and frankly are having difficulties (with
plastic BGAs) "popping off" the BGA
 to look at the solder joint.  Typically, we tend to fail at the interface
between the substrate (sometimes the PWB, sometimes the interposer) and the
pad rather than in the solder joint.  Now this happens EVEN on parts that
have gone through extensive li
fe testing (thermal cycle/shock) and gone "open".  We've cross sectioned
some parts and the solder joints (many of them) are in fact cracked.

I have a feeling there is a "technique" to this and I want to talk first
hand with a person that's "got the touch".

Thanks for your assistance.

--------------------------------------------------------
Jim Maguire
Boeing Phantom Works
E/E M&P
Phone (253)657-9063
Fax (253)657-8903
email:  [log in to unmask]
---------------------------------------------------------
---------------------------------------------------------
Jim Maguire
Boeing Phantom Works
E/E M&P
(253)657-9063
email:  [log in to unmask]
---------------------------------------------------------

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following
text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section
for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or
847-509-9700 ext.312
################################################################

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################